JP2013011039A - Device for producing carbon nanotube continuous fiber and producing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical device for stably and continuously producing a carbon nanotube continuous fiber.SOLUTION: A device for producing a carbon nanotube continuous fiber comprises: a tubular reactor 2 for continuously synthesizing a carbon nanotube from a carbon source, a catalyst and a carrier gas by use of flow gas phase CVD method; a cylindrical body 12 having an inner diameter within a range of 0.1-0.5 times as large as that of the tubular reactor, the cylindrical body being disposed downstream the tubular reactor; a pair of belt nip twisters 410 for twisting and feeding a sliver of carbon nanotube while sandwiching the sliver, which is continuously drawn from the tubular reactor; and a winding device 500 for continuously winding up the carbon nanotube continuous fiber thus obtained.

Description

  The present invention relates to a carbon nanotube continuous fiber manufacturing apparatus and a manufacturing method thereof.

  Carbon nanotubes (hereinafter referred to as CNTs) are attracting attention as a new material in the 21st century. However, technologies for continuous mass production and practical technologies for continuously and continuously producing continuous fibers made of CNTs are as follows: It has not yet been established as described below.

  That is, Patent Document 1 discloses a method in which CNTs are sequentially peeled from CNTs grown in a brush shape on a substrate by a substrate CVD method, and CNT fibers are twisted to obtain CNT fibers. However, since the CNT is synthesized only on the substrate, the length of the CNT continuous fiber obtained from one substrate is limited, so that it is not practical as a method for producing the CNT continuous fiber.

  Further, Patent Document 2 and Patent Document 3 show methods for obtaining CNT fibers by using a fluidized vapor phase CVD method capable of continuous synthesis of CNTs. In this synthesis method, continuous synthesis is possible by continuously introducing a carbon source and a catalyst as raw materials for CNT into the reaction system. However, both the method of Patent Document 2 in which CNT is wound around a horizontal screw rod provided in the reaction furnace, and the method of Patent Document 3 in which CNT fibers are wound using a spindle and a spool in a chamber directly connected to the synthesis furnace. This is a batch-type production method in which CNT fibers are taken out of the system after being wound, and is not suitable for producing continuous fibers.

  Furthermore, Patent Document 4 discloses a method of continuously synthesizing sliver-like yarns of carbon nanofibers using a fluidized gas phase CVD method and taking them out of the system. However, from the description of Examples and the like, it can be said that the yarn described in Patent Document 4 is a sliver-like yarn having a small bulk density, and is not a firmly twisted fiber.

  Further, Patent Document 5 discloses a method for producing a continuous CNT fiber in which a CNT generation process and a continuous fiberization process are directly connected, and the CNT is separated from exhaust gas and drawn from a reaction furnace into a fiber. Shows a method of twisting with a ring twister. However, when twisting with a ring twister, it is wound on a bobbin while applying tension to a fibrous material with a low strength. There is room.

  And although the method of obtaining the carbon fiber aggregate | assembly which consists of ultrafine single layer CNT whose diameter is 2 nm or less by the fluidized-phase CVD method is disclosed by patent document 6, there is no disclosure regarding continuous fiber.

  Moreover, although the polymer fiber which introduce | transduced CNT in the polymer material is shown by patent document 7, it improves the material characteristic of the polymer used as a base material to the last, and is different from a CNT continuous fiber. It is.

  On the other hand, although a nip twister known as a twisting method for drawing false twisting of synthetic fibers is shown in Patent Document 8, it has been devised exclusively as an apparatus for processing existing fibers, and is a novel fiber material. Application to certain CNTs was not disclosed. Further, even when the nip twister and the CNT synthesizer are combined, an appropriate CNT supply method does not exist, so that a CNT continuous fiber cannot be formed.

  Thus, no method has yet been found for producing CNT continuous fibers stably and continuously, safely and practically.

Special table 2008-517182 Special table 2007-536434 gazette Special table 2009-509066 gazette JP 2001-115348 A JP 2010-65339 A JP 2006-213590 A Japanese translation of PCT publication No. 2002-544356 Japanese Patent Laid-Open No. 06-184848

  An object of this invention is to provide the apparatus and method which can manufacture stably the CNT continuous fiber which can be used for practical use.

As a result of intensive studies by the present inventors in order to solve the above problems, the inventors have reached the following invention in order to stably obtain CNT continuous fibers.
(1) A tubular reactor for continuously synthesizing carbon nanotubes from a carbon source, a catalyst, and a carrier gas by a fluidized gas phase CVD method, and an inner diameter provided on the downstream side of the tubular reactor, Twisting while sandwiching a cylindrical body having a diameter in the range of 0.1 to 0.5 times the inner diameter, and a sliver of carbon nanotubes continuously provided from the tubular reactor provided downstream of the cylindrical body An apparatus for producing continuous carbon nanotube fibers, comprising: a belt nip twister having a pair of belts for feeding out continuous carbon nanotube fibers; and a winding device for continuously winding the obtained continuous carbon nanotube fibers.
(2) An exhaust hood for the gas discharged from the reaction furnace is provided at the downstream end of the cylindrical body, and the exhaust hood sucks and exhausts the atmosphere inlet, the atmosphere to be introduced, and the gas together. The carbon nanotube continuous fiber manufacturing apparatus according to (1), further comprising:
(3) A method for producing a continuous carbon nanotube fiber using the apparatus according to (1) or (2).
(4) Inserting the end of the threading rod, which is lower than the temperature inside the tubular reactor, into the tubular reactor, contacting the sliver-like carbon nanotube inside the tubular reactor, The carbon nanotube continuous fiber according to (3), wherein the sliver-like carbon nanotubes are guided to the belt nip twister by rotating and feeding while the other part is sandwiched by the belt twister to start the production of the carbon nanotube continuous fiber. Manufacturing method.
(5) A carbon nanotube continuous fiber obtained by the production apparatus according to (1) or (2) or the production method according to (3) or (4).

  In the present invention, the CNT continuous fiber is practically used in which a single filament or bundle of CNTs having a diameter of 0.6 nm to several tens of nm is macro-focused and processed to a thickness of several micrometers or more, for example. This refers to continuous fibers that are provided.

  According to the apparatus of the present invention, CNT continuous fibers can be obtained stably. In particular, CNT continuous fiber as an industrial material that is lightweight, high strength, and high conductivity can be mass-produced efficiently and inexpensively with a small number of processes. (Light motors, generators), lightweight conductive cables (power transmission lines, deep sea cables, etc.), etc.

It is a schematic sectional drawing of the manufacturing apparatus of the CNT continuous fiber which shows one Embodiment of this invention. It is a partial expanded sectional view of the isolation | separation part 300 in FIG. It is the upper side figure and side view of a belt nip twister. It is the schematic of a winding part. It is a schematic sectional drawing which shows the other aspect of the isolation | separation part 300 in FIG. It is a schematic sectional drawing which shows the other aspect of the isolation | separation part 300 in FIG. 10 is a schematic cross-sectional view of an apparatus used in Comparative Example 5. FIG.

  The apparatus of the present invention continuously synthesizes CNTs by a fluidized gas phase CVD method from a carbon source and a catalyst introduced together with a carrier gas into a tubular reactor, and continually CNTs fibers from sliver-like CNTs formed in the furnace. An apparatus for manufacturing, which is a CNT continuous fiber manufacturing apparatus provided with a pair of belt nip twisters that twists and feeds sliver-like CNTs while sandwiching them.

  There are roughly three types of CNT synthesis methods: arc discharge method, laser evaporation method, and CVD method (abbreviation of chemical vapor deposition method). The CVD method further includes a catalyst in the reaction system that rides in an air stream. There are roughly two types: a flowing gas phase CVD method and a substrate CVD method in which a catalyst is fixed to a substrate or the like in a reaction system. Among these synthesis methods, the fluidized gas phase CVD method is the most suitable method for continuous production of CNT because it can continuously synthesize CNT by continuously supplying the raw material catalyst and carbon source while spraying. It is. On the other hand, the substrate CVD method, the arc discharge method, and the laser evaporation method are unsuitable for continuous production because they are synthesized for each batch. Therefore, in the present invention, fluidized gas phase CVD can be preferably used.

  While the fluidized gas phase CVD method is suitable for continuous production of CNTs, CNTs synthesized while separating these carrier gases are often used instead of the atmosphere, such as argon or hydrogen, as the carrier gas. Is preferably taken out. Thus, as a result of intensive studies by the present inventors, the inventors have reached the invention of a CNT continuous fiber manufacturing apparatus equipped with a belt nip twister. With the apparatus according to the present invention, sliver-like CNTs can be continuously and safely taken out from a carrier gas atmosphere into the atmosphere, and CNT continuous fibers can be formed as they are.

  The CNT continuous fiber of this invention is manufactured using the apparatus shown, for example in FIG. The apparatus shown in FIG. 1 is provided on the downstream side of a reaction section 200 including a tubular reaction furnace composed of a reaction tube 2 and an electric furnace 1 that generate carbon nanotubes from a carbon source, a catalyst, and a carrier gas. The separation part 300 which isolate | separates and takes out produced | generated CNT from gas and dust, the twist part 400 which twists the taken-out CNT, and the winding part 500 of the obtained CNT continuous fiber are provided. The CNTs are generated in a tubular reactor in the reaction unit 200 and then guided to the cylindrical body 12 of the separation unit 300 by the carrier gas.

  The CNT pulled out from the reaction unit 200 to the separation unit 300 is one in which the CNTs of the smallest unit generated in the reaction tube 2 are gathered in a bundle by van der Waals force. One shape has a diameter of about 0.1 μm or less and a length of at least several tens of μm. In the apparatus of FIG. 1, continuous CNT fibers are obtained by continuously pulling out this bundle aggregate (sliver) while agglomerating into a fiber shape. For this purpose, a belt nip twister 410 is provided. The belt nip twister 410 can hold the sliver of the CNT bundle with a constant pressure. However, the CNT bundles constituting the sliver are brought into close contact with each other by intermolecular force, thereby contributing to the improvement of the strength of the CNT continuous fiber. Further, since the fibers are twisted and sent out at the same time as being sandwiched, the continuous fibers are twisted, and the tensile strength is increased by the winding effect of the fibers. In this way, even a yarn having a diameter so small that the carbon nanotube short fibers do not wrap around once is taken out as a continuous carbon nanotube twisted yarn-like continuous fiber directly from the reactor with a practical and simple configuration. I can do things.

  The details of the belt nip twister 410 are shown in FIG. The belt nip twister is arranged such that a pair of belts 41A and 41B are inclined and rotated so as to face each other and cross each other at a certain angle from the horizontal, and a contact point between the belts, that is, a nip point. , The yarn supplied from the upper part is sent out to the lower part, and at the same time, the yarn is arranged to be twisted while applying a compressive force and a frictional force.

  Specifically, the belt 41A and the belt 41B are arranged as shown in FIG. 3 by the drive pulleys 42A and 42B and the tension pulleys 43A and 43B so that the crossing angle θ is obtained. Here, the drive pulleys 42A and 42B are driven by a drive motor, but the two drive pulleys 42A and 42B may be driven by a single motor via a belt or gear, and a motor is installed in each. It may be driven.

  The crossing angle θ of the pair of belts is an angle formed on the upper side with respect to the nip point, and θ is preferably 60 ° to 120 °. More preferably, it is 80 ° to 100 °, but is not limited thereto. The crossing angle θ is set from a desired twisted yarn shape, and can be determined from the relationship between the yarn feed speed and the number of twists. The crossing angle θ is adjusted by rotating the brackets 44A and 44B around the axes 45A and 45B. Further, the angle formed by each belt from the horizontal direction and the number of rotations may be different, but it is usually preferable that they are the same.

  The position coordinate of the nip point is preferably directly below the central axis of the reaction tube 2 provided with the central axis in the vertical direction. You do n’t mind.

  The running direction of the belt is the direction of the arrow in FIG. 3 that twists while feeding the CNT sliver, and the belt is run so that the vertical vector of the belt when passing through the nip point is downward.

  The tension pulleys 43A, 43B and the like are desirably provided with a tension adjusting mechanism in order to give an appropriate tension to the belt. When the tension adjusting mechanism is not provided, it is preferable to use a belt material having a high elasticity such as urethane rubber.

  Further, the belt nip twister 410 is preferably provided with a mechanism for adjusting the pressure at the nip point and a mechanism for separating the belts from each other before starting threading. As the mechanism, for example, one bracket 46B is fixed, and the other bracket 46A is designed to be movable with the fulcrum shaft 47 as a base point by an air cylinder 48. According to such a mechanism, the position of the bracket 46A and the nip pressure can be adjusted by controlling the air cylinder 48, an appropriate clamping pressure is applied to the sliver-like CNT, and a gap is provided between the belts. can do.

  Furthermore, it is preferable to provide an upstream guide 49A immediately above the nip point and a downstream guide 49B immediately below. By using these guides, the yarn can be guided to the nip point more accurately, and the uniformity of the yarn can be improved.

  It is preferable to use a material with high elasticity for the material of the belt, and for the surface that contacts the yarn, select a material that generates moderate frictional force on the yarn, or such frictional force should be used. It is preferable to use one that has been post-processed to generate. As such a material, an elastomer such as urethane rubber is preferably used.

  The belt nip twister is effective for forming a twisted yarn having a diameter of 1 to 500 μm, for example. That is, since the twist angle, feed speed, and nip pressure can be independently changed, various control can be performed when a desired yarn is obtained. In addition, a feeding device such as a drawing roller is unnecessary, and a simple device can be achieved. It is also possible to apply pressure by applying a magnetic force to the nip point.

  The nip pressure by the belt 41A and the belt 41B is preferably as large as possible so that the belt is not damaged. Sliver-like CNTs can be made into continuous CNT fibers via a belt nip twister, but the strength of continuous fibers is increased by the close contact of CNT bundles with intermolecular force, so the CNT bundles are closely attached. It is preferable to apply a pressure sufficient to allow this.

  The twist angle of the CNT continuous fiber is determined by a plurality of factors such as the diameter of the CNT continuous fiber, the rotational speed in the twist direction of the belt nip twister, and the distance from the twister to the take-up bobbin. In particular, the rotational speed in the twisting direction of the belt nip twister is a major factor in controlling the twist angle, and therefore it is preferable to adjust appropriately. The twist angle refers to the angle of the fine fiber bundle seen on the continuous fiber surface with respect to the long axis direction of the continuous fiber. The twist angle is preferably 5 to 45 °, more preferably 15 to 40 °. By twisting, the tensile strength of the yarn can be increased due to the winding effect of the fiber, but if too much twist is applied, thread breakage may occur, or double twisting may occur when the yarn is unwound from the bobbin. It is not preferable because it becomes On the other hand, when the twist is too shallow, the yarns wound around the bobbin are brought into close contact with each other, causing problems such as easy breakage when the yarn is unwound from the bobbin.

  By the nip belt twister as described above, the sliver-like CNTs are twisted and fed out while being held at a predetermined pressure, and become CNT continuous fibers. At this time, since there is no fulcrum that suppresses the rotation of the sliver on the upper side of the sliver, twisting is applied from the nip point to the upper portion with an open end. As a result, in the vicinity of the upstream guide 49A, the twist is also transmitted to the sliver-like CNTs, and the twisted state is obtained. For this reason, the sliver-like CNTs are more stably guided to the guide and the nip point.

  Furthermore, in the present invention, a cylindrical body having an inner diameter of 0.1 to 0.5 times the inner diameter of the tubular reactor is provided upstream of the belt nip twister and downstream of the tubular reactor. Provide. Specifically, in the apparatus shown in FIGS. 1 and 2, the inner diameter of the reaction tube 2 is 0.1 to 0 on the downstream side of the reaction tube 2 constituting the tubular reaction furnace and on the upstream side of the belt nip twister 410. A cylindrical body 12 having a five times inner diameter is provided.

  When the ratio of the inner diameter of the cylindrical body to the inner diameter of the tubular reactor exceeds 0.5, the sliver-like CNT can be guided out of the tubular reactor, but from the central portion of the tubular reactor circle. This is not preferable because it tends to be eccentric outward and the passage position becomes unstable. On the other hand, if this ratio is less than 0.1, sliver-like CNTs adhere to the inner wall of the cylindrical body 12 and the frequency of thread breakage increases, which is not preferable. The ratio of the inner diameter is preferably 0.2 to 0.3. In the present invention, the inner diameters of the tubular reaction furnace and the tubular body mean the minimum inner diameters of the tubular reaction furnace and the tubular body, respectively.

  In the apparatus shown in FIGS. 1 and 2, the cylindrical body 12 also functions as an exhaust port of the tubular reaction furnace, but the carrier gas and the sliver-like CNT pass through the inside of the cylindrical body 12 in this way. By designing so as to increase the linear velocity of the carrier gas in the cylindrical body 12, the sliver-like CNT is less likely to adhere to the inner wall of the cylindrical body 12, and the center is guided more stably in the downstream direction. Can do. Since the linear velocity of the sliver-like CNT inside the reaction tube is higher than the linear velocity of the carrier gas, it is known that the sliver is easily bent. Therefore, a portion where the linear velocity of the carrier gas is large is provided at an arbitrary location after the outlet of the reaction tube, the sliver CNTs are pulled in the downstream direction, and the sliver is linearly controlled to control the sliver CNTs with the belt nip twister. Can be guided stably.

  The cylindrical body may be anything as long as the minimum diameter portion is in the above range, but preferably has a funnel shape as shown in FIGS. Furthermore, by using a funnel-shaped cylindrical body having a collection angle of 30 to 120 degrees toward the top, the probability that the sliver-like CNT adheres to the inner wall can be further reduced, and the probability of yarn breakage is small. A more uniform yarn can be obtained. Here, the funnel surface is preferably a surface with a small coefficient of friction, and for example, it is preferable that a surface treatment that prevents CNTs to adhere is applied. Further, the shape of the funnel may be a cone, a triangular pyramid, or a quadrangular pyramid. When a later-described reflecting mirror 22 for observation inside the furnace is provided, the funnel is preferably transparent glass. Furthermore, a cylinder with a large inner diameter may be further connected directly above the cylindrical body 12.

  A separation box 10 made of glass or quartz is preferably provided around the cylindrical body 12 as shown in FIG. By providing the separation box 10, the temperature difference between the tubular reactor and the tubular body 12 can be reduced, and the production status of sliver-like CNTs can be observed as needed. The separation box 10 is preferably provided with a pressure monitoring side hole 31 and further provided with a water column differential pressure gauge so that the pressure in the tubular reactor can be monitored at any time.

  Furthermore, the downstream end of the cylindrical body 12 provided downstream from the outlet of the tubular reactor was provided with an exhaust pipe 15 or the like for sucking together the gas discharged from the tubular reactor and the atmosphere. An exhaust hood 16 is preferably provided. In the CVD method, hydrogen is often used as a carrier gas and hydrocarbon gas is used as a raw material gas. With the configuration described above, these combustible gases are safely exhausted, and CNTs are safely separated into the atmosphere. Can be taken out. If such an exhaust hood is not provided, CNT continuous fibers can be formed, but combustible gas diffuses around the outside of the exhaust port 14 and reaches the heater part of the tubular reactor to cause a fire / explosion. Increased risk of occurrence. Therefore, it is preferable to ensure safety by separately providing a local exhaust device that sucks and exhausts these combustible gases together with the atmosphere.

  An example of the structure of the exhaust hood is as shown in FIG. The sliver-like CNT generated in the tubular reactor is guided to the atmosphere through the exhaust port 14 and the guide 17 of the cylindrical body 12, but in order to prevent the sliver-like CNT from breaking, In order not to completely seal 200, a gap is provided around the sliver-like CNT to be induced. Further, an exhaust pipe 15 is provided on the side of the space between the exhaust port 14 and the guide 17 so that a large amount of air does not flow into the tubular reactor from the gap. The exhaust pipe 15 is designed to exhaust at a flow rate higher than the flow rate of the gas exhausted from the reaction tube 2 and to exhaust while mixing both the exhaust gas and the atmosphere.

  Here, if the amount of air sucked is too large, the air will vigorously flow backward from the guide 17, making it difficult to stably discharge the sliver-like CNTs. Therefore, an air hole 20 is provided in an intermediate portion of the exhaust pipe 15, and a slider cylinder 19 is provided so that the suction amount can be adjusted. By adjusting the amount of air sucked in the vicinity of the exhaust pipe using the slider cylinder 19 in this way, it becomes easy to safely and stably take out the sliver-like CNT into the atmosphere, and as a result, the CNT continuous fiber can be more stable. Can be manufactured. The exhaust gas needs to be diffused and exhausted into the atmosphere after being diluted to a concentration lower than the explosive limit concentration. By adopting the above-described configuration, the exhaust gas can be quickly discharged from the exhaust port 14 in the vicinity of the atmospheric hole 20. It will be diluted with the atmosphere, and as a result, safety can be improved. In addition, by installing such an exhaust hood, not only gas components but also diffusible CNT, carbon particulates, and unreacted catalyst particulates can be discharged together with exhaust, and in the vicinity of the CNT continuous fiber manufacturing equipment It is possible to improve the safety for workers in Since the exhaust gas discharged from the exhaust pipe 15 is likely to contain fine dust, it is preferable that the exhaust gas is diffused and exhausted to the outside through a high-performance filter.

  Further, the exhaust hood need not be provided with a slider cylinder. For example, the amount of gas discharged from the tubular reactor and the amount of gas sucked into the exhaust port 15 are measured, and the amount of air obtained by subtracting the amount of exhaust from the amount of sucked air is introduced into the side of the exhaust hood or the like. It can also be introduced from the mouth while being controlled by a mass flow controller. By doing so, it is possible to provide the same function as when the above-described slider cylinder is used. The apparatus configuration is not limited to the above as long as the amount of gas exhausted from the tubular reactor, the amount of gas sucked from the exhaust port 15, and the amount of air sucked in can be controlled.

  A guide 17 is joined to the downstream end of the exhaust hood in the fiber travel direction. For this, it is preferable to use a ceramic that is non-magnetic and wear-resistant and has low running resistance. In addition, it is preferable that the position of the guide 17 and the nip point by the belt nip twister 410 are made as close as possible so that the sliver-like CNTs or CNT continuous fibers can run stably.

  The CNT continuous fiber manufacturing apparatus of the present invention also includes a winding device for continuously feeding CNT continuous fibers. Specifically, for example, as shown in FIGS. 1 and 4, the winding unit 500 may be configured to wind up the CNT continuous fiber sent from the upper part around the bobbin 51. A method of rotating the bobbin 51 while reciprocating in the horizontal direction is desirable, but the method is not limited as long as the winder can wind the CNT continuous fiber (twisted yarn) F at a constant tension or a constant speed. For example, a system in which a yarn path guide 55 is provided on the upstream side of the bobbin 51 and the CNT continuous fiber is swung left and right by the yarn path guide 55 can be used.

  Hereinafter, a case where the bobbin 51 shown in FIG. 4 is wound while being reciprocated in the horizontal direction will be described. First, the bobbin holder 53 can reciprocate in the forward and reverse directions by a screw fixed to the variable speed motor M2 and the gantry 52. The bobbin 51 is held by a system that can be detached from the bobbin holder 53. The variable speed motor M1 and the control device 54 have a system for gradually reducing the rotational speed so that the winding speed becomes constant even when the winding diameter increases. The winding diameter is calculated from a value measured by a non-contact winding thickness sensor 56 attached in the vicinity of the yarn path guide 55 provided on the axis of the motor M1, and is sent to the control device 54. Further, the winding shape can be changed by controlling the traverse width of the variable speed motor M2 in accordance with the winding diameter. Further, the non-contact winding thickness sensor 56 having the function of a thread breakage sensor is configured to detect a winding around the belt or an abnormal accumulation of CNT bundles in the separation unit 300 and perform recovery treatment.

  The rotation speed of the bobbin 51 is preferably matched with the supply speed of the CNT continuous speed fiber, and is preferably 5 to 10% faster than the supply speed in order to slightly apply tension. The bobbin 51 can be made of a general-purpose material such as stainless steel or plastic.

  In the CNT continuous fiber manufacturing apparatus as described above, the sliver-like CNT started to be generated in the tubular reactor is guided to the carrier gas and directed to the exhaust pipe 15. At this time, the sliver-like CNT moves toward the outlet without being attached to the inner wall inside the reaction tube 2 having an electric furnace around it, but the temperature of the sliver-like CNT exits the reaction tube 2 having an electric furnace around it. When it reaches the lowering area, it tends to adhere to the inner wall. Therefore, the end of a heat-resistant threading rod (for example, a stainless steel rod having a diameter of 1 to 2 mm) that is lower in temperature than the temperature inside the tubular reactor using the property that CNT adheres to a lower temperature. The part is inserted into the tubular reactor, and is brought into contact with and attached to the sliver-like carbon nanotubes, and the other part of the threading rod (the part not in contact with the sliver-like CNT) is rotated and sent out while being sandwiched by the belt twister. By doing so, it is preferable to start the production of CNT continuous fibers by guiding the sliver-like carbon nanotubes to the belt nip twister. In addition, it is preferable that the surface of this bar is finely uneven so as not to be glossy, and by doing so, the adhesion force of the sliver-like CNTs taken up to the bar can be improved.

  The sliver-like CNT adhering to one end of the threading rod is sufficiently entangled with the rod and guided downward because the other portion of the threading rod is rotated by the belt nip twister. At this time, since the rotation speed depends on the diameter of the rod, the diameter of the rod is ideally the same diameter as the desired CNT continuous fiber, for example, about 10 to 500 μm, in order to more reliably twist, but the length In order to maintain the strength of a bar of several tens of centimeters, a thickness of 0.5 to 5 mm in diameter is preferable. Therefore, the diameter of the bar needs to be optimized and selected from the scale of the apparatus and the strength of the bar, but more preferably the diameter is 0.5 to 2 mm.

  Any material can be used as the material for the threading rod as long as the shape can be maintained at the temperature inside the tubular reactor, and stainless steel or ceramics is preferable. In addition, iron, titanium, molybdenum, tungsten, zirconium, and the like, and alloys and oxides containing them can also be used.

  The length of the threading rod must be at least the distance from the lower end of the electric furnace of the tubular reactor to the nip point in the fiber running direction, and the length for handling is about 20 cm. The length added is preferably. Specifically, about 30-100 cm is preferable.

  The sliver-like CNT attached to one end of the threading rod becomes a CNT continuous fiber by passing through the belt nip twister, but the CNT continuous fiber is still attached to the threading rod even when it is a continuous fiber. It is. For this reason, it is preferable to further guide the threading rod with the CNT continuous fibers attached to the winding unit 500 and thread the bobbin. After threading the bobbin, it is only necessary to start continuous winding by cutting the CNT continuous fiber near the tip of the threading rod.

  As a means for guiding one end of the CNT continuous fiber after passing through the belt nip twister to the winding device, it is effective to use a suction gun 80 as shown in FIG. The suction gun 80 is used when the CNT continuous fiber is first guided between the belt nip twister 410 and the winding unit 500 to thread it onto the bobbin, or when the yarn breakage occurs, the upstream side where the yarn breakage occurs. It can be used to capture the edge and guide it to the bobbin. An air suction port is provided at the tip of the suction gun, and the CNT continuous fiber is sucked together with a large amount of air, and one end of the yarn can be guided to an arbitrary place with a constant suction force, that is, a constant tension. . The suction gun 80 is a known device used in a fiber production facility, and has a mechanism for blowing compressed air downstream and generating a suction force at an upstream suction port.

  In addition, the suction gun 80 is temporarily fixed to the side through which the CNT continuous fiber passes, and suction is stopped in normal times, and suction is started by introducing compressed air by a thread break signal or a bobbin switching signal. It is also possible to automate such as inducing.

  The air introduced into the suction gun 80 and the air sucked from the suction port can be exhausted through a finely woven bag cloth provided on the downstream side. In this way, the sucked CNT can be captured and prevented from being scattered around.

  The CNT continuous fiber manufacturing apparatus of the present invention can be provided with a reflecting mirror or monitor camera, an endoscope, etc. for observing the inside of the tubular reactor. For example, as shown in FIG. 2, the inside can be observed by providing a mirror 22 in the tubular reactor. By making the inside observable in this way, it is possible to monitor the sliver-like CNT during threading, the supply state of the produced CNT, and the state in which the CNT raw material is spray-supplied from the nozzle. In particular, it is useful when inserting a threading rod and attaching sliver-like CNTs. It can also be used for quality control and maintenance of produced CNTs.

  Then, by observing the inside, it is possible to grasp the production process of the sliver-like CNT and the twisting effect from the belt nip twister. In the reaction furnace, the CNTs start to self-aggregate before and after the cooling start position and become a sliver. At this time, the CNTs are gathered by the cohesive force between the CNTs, and therefore the direction of the CNT single yarn is usually random. However, when twisting with a belt nip twister, the upper end of the sliver-like CNT is an open end, so the twist is transmitted to the upper part, and when the CNT becomes sliver, the CNT single yarn is aligned to some extent at the free end above the sliver. That is, they are aggregated and trapped while being oriented.

  In order to sufficiently function the twisting mechanism, it is preferable to shorten the distance between the nip point of the belt nip twister and the lower end portion of the electric furnace of the tubular reactor (lower limit of the heating region) in the fiber running direction. . Specifically, the distance from the lower end of the electric furnace of the tubular reaction furnace to the nip point of the belt nip twister is preferably 3 to 12 times the inner diameter of the reaction tube 2. By making this range, the retroactive twist is easily transmitted to the upstream part, the influence of disturbance resistance due to the running direction is reduced, and the aggregation and converging point at the lower end of the heating area is stabilized. Uniform CNT continuous fibers can be obtained. If the distance is smaller than three times, the temperature near the nip point becomes 250 ° C. or more when the set temperature of the electric furnace is set to 1200 ° C., which is not preferable because the nip belt is likely to be deformed. On the other hand, when it exceeds 12 times, although a CNT continuous fiber can be formed, the twist tends to be unstable.

  In addition, when shortening the distance from the lower end part of the electric furnace of the tubular reactor to the nip point of the belt nip twister, it is preferable to consider the heat resistance of the components provided therebetween. For example, it is desirable to provide a flange that supports the reaction tube immediately below the reaction tube 2, but it is preferable to use a material such as SUS. Moreover, it is preferable to provide the separation box 10 around the cylindrical body under the reaction tube 2, but the material is preferably glass or quartz. Furthermore, it is preferable to provide packing at the connection portion between the flange and the separation box, but it is preferable to use a graphite sheet having excellent heat resistance for the packing.

  In addition, as shown in FIG. 2, it is also preferable to arrange a sensor 23 that reads the thickness unevenness of the sliver-like CNTs or CNT continuous fibers by changing the electrostatic capacity. Thus, when the sensor 23 is arranged on the side surface of the sliver-like CNT or CNT continuous fiber, the thickness unevenness and thread breakage can be constantly monitored by the monitor signal from the sensor. Then, (i) change the discharge amount of the input stock solution or the input amount of the carrier gas, or (ii) change the speed of the belts 41A and 41B so that the thickness of the CNT continuous fiber falls within the desired range by this monitor signal. Or (iii) feedback control of the nip pressure at the belts 41A and 41B with the operating pressure of the air cylinder 48 (FIG. 3), or (iv) change of the winding speed of the bobbin 51. .

  The synthesis of CNTs in the apparatus as described above can be performed, for example, as follows using a fluidized gas phase CVD method and using a known material. That is, the central part in the vertical direction of the reaction tube 2 is heated to 600 to 1200 ° C. by the electric furnace 1, and carrier gas and CNT raw material are introduced from the upper part of the reaction tube 2 to synthesize CNT. Since a liquid is used as a raw material, the mixed solution 4 of the liquid raw material is quantitatively supplied using a microfeeder 5 and sprayed into a reaction tube by a carrier gas and a nozzle provided in the apparatus. The raw material supplied to the reaction tube 2 is heated and vaporized, further pyrolyzed, and CNT grows starting from the particulate iron catalyst. The CNT grows and is sent downstream by the carrier gas to finish the growth. It is preferable that the CNT produced | generated at this time is so high that the density | concentration of CNT which exists per unit volume of carrier gas can self-aggregate CNT. Here, self-aggregation means that the bundled CNTs aggregate in a macro manner in addition to the aggregation of the individual CNTs in a bundle shape. By-product dust can also be separated by utilizing the cohesive force between CNTs. In other words, by-products such as soot made of amorphous carbon and catalyst waste that did not contribute to the synthesis reaction have a property of diffusing into the carrier gas, while the produced CNT has a property of aggregating in the carrier gas. For some reason, CNTs aggregate while by-products separate from CNTs. As a result, a CNT continuous fiber having a high CNT purity is obtained.

  As the carbon source of the CNT raw material, it is preferable to use hydrocarbons, which may be one kind or plural kinds. Although there is no particular limitation, it is preferable to use at least one liquid that can dissolve a catalyst and a reaction accelerator described later. Examples of the hydrocarbon may be an acyclic saturated aliphatic hydrocarbon such as hexane, heptane, octane, nonane, decane, dodecane, and tetradecane, or an isomer having a branched structure instead of a straight chain. It may be an acyclic unsaturated aliphatic hydrocarbon having one or more double bonds. Cyclic saturated aliphatic hydrocarbons such as cyclohexane, decalin, and tetradecahydrophenanthrene, and cyclic unsaturated hydrocarbons such as benzene, toluene, xylene, and tetrahydronaphthalene may be used. Alcohols such as ethanol, propanol and butanol can also be used. Of these carbon sources, decalin, ethanol, and toluene are preferably used. A liquid carbon source can be used by dissolving a metal complex or suspending and dispersing fine metal particles.

  The catalyst is not particularly limited by the kind of metal or the form of the metal, but a transition metal compound or a transition metal ultrafine particle (for example, a metal cluster of about 1 nm) is preferably used. The transition metal compound can generate transition metal particles as a catalyst by being decomposed in a reaction tube.

  These transition metal compounds and transition metal atoms are preferably supplied in a gaseous state to a reaction region maintained at a temperature of 600 to 1200 ° C. in the reaction tube, and before being heated to a predetermined reaction temperature. Those that can be completely vaporized are preferred.

  Examples of the transition metal atom include iron, nickel, cobalt, scandium, titanium, vanadium, chromium, manganese, and the like, among which iron, nickel, and cobalt are more preferable.

  As a transition metal compound, an organic transition metal compound, an inorganic transition metal compound, etc. can be mentioned, for example. Examples of the organic transition metal compound include ferrocene, nickelocene, cobaltcene, iron carbonyl, iron acetylacetonate, iron oleate, and the like, and ferrocene is more preferable. Examples of the inorganic transition metal compound include iron chloride.

  A plurality of types of carbon sources can be added, and the second carbon source can be a gaseous source at room temperature. For example, methane, ethane, propane, acetylene, ethylene, propylene and the like are used, and among them, ethylene is preferably used.

  Furthermore, it is also preferable to add a reaction accelerator to the raw material. Sulfur compounds are preferably used because they interact with the metal catalyst and contribute to the promotion of CNT production. As the sulfur compound, both organic sulfur compounds and inorganic sulfur compounds are used, but sulfur-containing heterocyclic compounds such as thianaphthene, benzothiophene, and thiophene are more preferable, and thiophene is more preferable. If the reaction accelerator is a gas, it is mixed with a carrier gas and introduced into the reaction tube. If it is a liquid, it is mixed and dissolved in a liquid carbon source and introduced into the reaction tube by nozzle spraying.

  As described above, the raw material supply line can be selected according to the type of the carbon source. When the liquid raw material and the gaseous raw material are used at the same time, it is preferable to use both.

  The carrier gas is preferably hydrogen, argon, or nitrogen, and may be a single gas or a mixed gas. Preferably, hydrogen gas alone or argon gas containing hydrogen is used.

  In the present invention, in order to facilitate the formation of sliver-like CNTs, it is preferable to set the linear velocity in the reaction tube to be 5 to 50 cm / min by reducing the amount of carrier gas. If it is slower than 5 cm / min, the produced CNTs are likely to diffuse and CNTs do not self-aggregate, which is not preferable. On the other hand, if it exceeds 50 cm / min, the proportion of CNTs transported to the carrier gas increases, and CNTs are less likely to self-aggregate. In addition, the linear velocity said here is the value which divided the flow volume of the supplied gas by the cross-sectional area inside a reaction tube. When the gas passes through the heating zone, the gas expands and the linear velocity slightly increases. However, since the measurement is difficult, the volume of the gas at room temperature is used as a reference for calculation here.

  A method of increasing the carbon source concentration in the carrier gas unit volume is also effective. Specifically, it is preferable that the weight ratio of carbon atoms is 25 to 50% by weight among all the raw materials including the carrier gas. By setting it within this range, sliver-like CNTs with high CNT purity can be obtained. If the carbon source is less than 25% by weight, the concentration of the produced CNTs is small, and CNTs are difficult to self-aggregate. If it exceeds 50% by weight, the amount of by-products such as soot increases, and the purity of the CNT tends to decrease.

  The temperature of the electric furnace 1 is preferably 600 to 1200 ° C. By setting the temperature within this range, the catalyst metal can be made fine particles, and further, the carbon source can be decomposed into a state where CNTs are easily generated, so that CNTs can be obtained with high purity and high efficiency. If it exceeds 1200 ° C., the ratio of decomposition and generation tends to be biased toward decomposition, which is not preferable because the yield decreases. On the other hand, CNT can be synthesized even at a temperature lower than 600 ° C., but this is not preferable because adverse effects such as a decrease in the yield of CNT and an easy attachment of CNT to the inner wall occur.

  Below, the manufacture example of the CNT continuous fiber of this invention is demonstrated concretely. However, the present invention is not limited to the following examples.

<Formability of CNT continuous fiber>
Considering that CNT continuous fibers are likely to be defective at 10 to 40 cm immediately after the start of formation, the formability was evaluated by whether or not CNT continuous fibers could be formed continuously by 50 cm or more. The case where a continuous CNT continuous fiber of 50 cm or more can be formed is shown in the table as ○, and the case where it cannot be formed as x.

<Bulk density of CNT continuous fiber>
The bulk density of the CNT continuous fiber was measured. When the bulk density is 0.1 g / cm ³ or more, a tensile strength that can withstand winding can be obtained.

  Regarding the bulk density, a 1 cm yarn of 10 cm to 11 cm from the first end of the yarn, a 1 cm yarn of the central portion, and a 1 cm yarn of 10 cm to 11 cm from the end are separated, and three diameters are obtained using an optical microscope. The weights were measured, the bulk density at each location was calculated therefrom, and the average at 3 locations was calculated and shown in the table. In addition, when the variation in diameter and bulk density is within ± 20% of the average value, it is indicated as ◯, and when not, it is indicated as x.

<Example 1>
1 to 4, a total of 0.4 L / min of hydrogen as a carrier gas, 20 μL / min of a decalin solution containing 4 w% of catalyst ferrocene and 2 w% of thiophene as an additive, 3 mL / min of ethylene gas as a carbon source was charged into the reaction tube 2 set at 1200 ° C. by the electric furnace 1. At this time, the weight ratio of carbon atoms in all the input materials including the carrier gas is 32.2 w%. The inner diameter of the reaction tube 2 was 52 mm, the inner diameter of the cylindrical body 12 was 14 mm, and the ratio between the inner diameters was 0.27. The cylindrical body 12 was a funnel shape. When the apparatus was operated under these conditions, it was confirmed that a sliver-like CNT having a diameter of about 7 mm was generated inside the reaction furnace through a reflecting mirror for confirming the inside.

  Next, the belt nip twister feed speed and the winding speed at the winding section are set to 2.5 m / min, and a stainless steel rod having a diameter of 1 mm, a length of 60 cm, and about 20 ° C. is placed under the belt nip twister. The tube was inserted from the side into the tubular reactor through the cylindrical body 12, and sliver-like CNTs were attached to the tip of the rod. The sliver-like CNTs are entangled with the rotating belt nip twister and pulled downstream at a feed rate of 2.5 m / min. The CNT continuous fiber was formed as it was passed through and guided to the intersection of the belt nip twister. Next, the CNT continuous fiber was removed from the stainless steel rod, and the tip of the CNT continuous fiber was sucked into the suction gun 80. Thereafter, the suction port of the suction gun 80 was slowly guided to the winding bobbin, the CNT continuous fiber was wound on the bobbin, the suction gun was removed, and the continuous winding of the CNT continuous fiber was performed. As a result, the CNT continuous fiber could be wound up stably for 4 minutes or longer, that is, 10 m or longer.

The average value of the diameter of this CNT continuous fiber was 40 μm, and the average value of the bulk density was 0.5 g / cm ³ . The diameter and bulk density at the initial end, the central portion, and the terminal end were all within an average value of ± 20%, and the CNT continuous fiber was uniform.

<Example 2>
The cylindrical body 12 was not the funnel shape as shown in 12 of FIG. 2, but was changed to a cylindrical body (inner diameter 14 mm) having a step as shown in 12 of FIG. . As a result, the CNT continuous fiber could be continuously wound up for 4 minutes or more, that is, 10 m or more. The obtained CNT continuous fibers had a diameter (average value) of 40 μm and a bulk density (average value) of 0.5 g / cm ³ . The diameter and bulk density at the initial end, the central part, and the terminal part were all within an average value of ± 20%, and the CNT continuous fiber was uniform.

<Example 3>
The same operation as in Example 1 was performed except that the amount of hydrogen as the carrier gas was increased from 0.4 L / min to 0.7 L / min and the input amount of the decalin solution was increased from 20 μL / min to 30 μL / min. In addition, the weight ratio of the carbon atoms in all the input materials including the carrier gas was 28.1 w%. As a result, the CNT continuous fiber could be wound up stably for 4 minutes or longer, that is, 10 m or longer. The obtained CNT continuous fibers had a diameter (average value) of 40 μm and a bulk density (average value) of 0.5 g / cm ³ . The diameter and bulk density at the initial end, the central part, and the terminal part were all within an average value of ± 20%, and the CNT continuous fiber was uniform.

<Example 4>
The same operation as in Example 1 was performed except that the inner diameter of the cylindrical body 12 was changed from 14 mm to 26 mm and the ratio of the inner diameter of the cylindrical body 12 and the reaction tube 2 was changed to 0.5. As a result, the CNT continuous fiber could be wound up stably for 4 minutes or longer, that is, 10 m or longer. The obtained CNT continuous fibers had a diameter (average value) of 40 μm and a bulk density (average value) of 0.5 g / cm ³ . The diameter and bulk density at the initial end, the central part, and the terminal part were all within an average value of ± 20%, and the CNT continuous fiber was uniform.

<Example 5>
The same operation as in Example 1 was performed except that the inner diameter of the cylindrical body 12 was changed from 14 mm to 6 mm and the ratio of the inner diameter of the cylindrical body 12 and the reaction tube 2 was changed to 0.12. As a result, the CNT continuous fiber could be wound up stably for 4 minutes or longer, that is, 10 m or longer. The obtained CNT continuous fibers had a diameter (average value) of 10 μm and a bulk density (average value) of 0.5 g / cm ³ . The diameter and bulk density at the initial end, the central part, and the terminal part were all within an average value of ± 20%, and the CNT continuous fiber was uniform.

<Example 6>
The same operation as in Example 1 was performed except that the number of belts of the belt nip twister 410 was changed from one on one side to two on one side, that is, a total of four. As a result, the CNT continuous fiber could be wound up stably for 4 minutes or longer, that is, 10 m or longer. The obtained CNT continuous fiber had a diameter (average value) of 30 μm and a bulk density (average value) of 0.4 g / cm ³ . The diameter and bulk density at the initial end, the central part, and the terminal part were all within an average value of ± 20%, and the CNT continuous fiber was uniform.

<Example 7>
The inner diameter of the reaction tube 2 was changed from 52 mm to 105 mm, the ratio of the inner diameter of the cylindrical body 12 and the reaction tube 2 was changed to 0.13, the carrier gas flow rate was changed from 0.4 L / min to 1.6 L / min, The same operation as in Example 1 was performed except that the input amount was changed from 20 μL / min to 80 μL / min. As a result, the CNT continuous fiber could be wound up stably for 4 minutes or longer, that is, 10 m or longer. The obtained CNT continuous fibers had a diameter (average value) of 60 μm and a bulk density (average value) of 0.5 g / cm ³ . The diameter and bulk density at the initial end, the central part, and the terminal part were all within an average value of ± 20%, and the CNT continuous fiber was uniform.

<Example 8>
Example 1 was performed except that the exhaust hood was not provided as shown in FIG. As a result, the CNT continuous fiber could be continuously wound up for 4 minutes or more, that is, 10 m or more. The obtained CNT continuous fibers had a diameter (average value) of 40 μm and a bulk density (average value) of 0.5 g / cm ³ . The diameter and bulk density at the initial end, the central part, and the terminal part were all an average value of ± 20%, and although they were more uneven than other examples, CNT continuous fibers were obtained almost uniformly.

<Comparative Example 1>
The same operation as in Example 1 was performed except that the belt nip twister 410 was removed, and the sliver-like CNT was directly wound on the winding bobbin. As a result, the sliver-like CNTs were continuously wound up stably for 4 minutes or more, that is, equivalent to 10 m or more. The CNT continuous fiber could not be obtained.

<Comparative example 2>
The same operation as in Example 1 was performed except that the inner diameter of the cylindrical body 12 was changed from 14 mm to 52 mm and the ratio of the inner diameter of the cylindrical body 12 and the reaction tube 2 was changed to 1.0. As a result, although sliver-like CNTs could be stably generated, a CNT continuous fiber having a length of 50 cm or more could not be obtained because a positional shift occurred from the intersection of the belt nip twister.

<Comparative Example 3>
The same operation as in Example 1 was performed except that the inner diameter of the cylindrical body 12 was changed from 14 mm to 32 mm and the ratio of the inner diameter of the cylindrical body 12 and the reaction tube 2 was changed to 0.62. Although sliver-like CNTs could be stably generated, a CNT continuous fiber having a length of 50 cm or more could not be obtained because a positional shift occurred from the intersection of belt nip twisters.

<Comparative example 4>
The same operation as in Example 1 was performed except that the inner diameter of the cylindrical body 12 was changed from 14 mm to 3 mm and the ratio of the cylindrical body 12 and the inner diameter of the reaction tube 2 was set to 0.058. Although sliver-like CNTs could be stably produced, sliver-like CNTs were clogged at the upper entrance of the cylindrical body, and continuous CNT fibers having a length of 50 cm or more could not be obtained.

<Comparative Example 5>
As shown in FIG. 7, the same operation as in Example 1 was performed except that the nip belt twister was changed to a ring twister. Although the CNT continuous fiber could be wound up by 10 m or more, the average value of the bulk density was 0.05 g / cm ³ , and many yarn breaks occurred when the wound yarn was unwound.

1 Electric furnace
2 reaction tubes
3 Spray nozzle
4 Mixed solution
5 Micro feeder
6 Carrier gas flow meter
7 Carrier gas
8 Flange 9 Packing sheet 10 Separation box
11 Fastening ring
12 Tubular body 13 O-ring 14 Exhaust port 15 Exhaust pipe 16 Exhaust hood
17 Guide
18 Atmosphere 19 Slider cylinder 20 Atmosphere hole 21 Internal camera 22 Mirror 23 Thickness unevenness sensor 30 Yarn stick 31 Pressure monitoring side holes 41A, 41B Belts 42A, 42B Drive pulley
43A, 43B Tension pulleys 44A, 44B Brackets 45A, 45B Shafts 46A, 46B Bracket 47 Support shaft 48 Air cylinder 49A Upstream guide 49B Downstream guide 51 Bobbin
52 Stand 53 Bobbin holder 54 Controller 55 Thread guide 56 Non-contact roll thickness sensor 61 Stretched pair roll 62 Ring rail 63 Bobbin 200 Reaction unit 300 Separating unit 400 Twisting unit 410 Belt nip twister 500 Winding unit 600 Ring twister F CNT continuous Fiber NP Nip point

Claims (5)

  A tubular reaction furnace for continuously synthesizing carbon nanotubes from a carbon source, a catalyst, and a carrier gas by a fluidized gas phase CVD method, and an inner diameter provided on the downstream side of the tubular reaction furnace is 0 of the inner diameter of the tubular reaction furnace. .1 to 0.5 times the range of the tubular body and carbon nanotube sliver continuously drawn from the tubular reactor provided downstream of the tubular body, and twisted while sandwiching carbon An apparatus for producing continuous carbon nanotube fibers, comprising: a belt nip twister including a pair of belts for feeding the continuous nanotube fibers; and a winding device for continuously winding the obtained continuous carbon nanotube fibers.   An exhaust hood for gas exhausted from the reaction furnace is provided at the downstream end of the cylindrical body, and the exhaust hood includes an air inlet and means for sucking and exhausting the introduced air and the gas together. The carbon nanotube continuous fiber manufacturing apparatus of Claim 1 provided.   The manufacturing method of the carbon nanotube continuous fiber using the apparatus of Claim 1 or 2.   Insert the end of the threading rod, which is lower than the temperature inside the tubular reactor, into the tubular reactor, contact the sliver-like carbon nanotube inside the tubular reactor, and the other part of the threading rod The carbon nanotube continuous fiber manufacturing method according to claim 3, wherein the sliver-like carbon nanotubes are guided to the belt nip twister by rotating and feeding them while being held by a belt twister to start manufacturing the carbon nanotube continuous fibers.   A carbon nanotube continuous fiber obtained by the production apparatus according to claim 1 or 2 or the production method according to claim 3 or 4.